Guns at scene of mass shooting in Western Australia belonged to grandfather

Three guns found at the scene of the mass shooting that killed seven in Western Australia on Friday are registered to the four dead children's grandfather.

The seven dead have been named as Cynda and Peter Miles, their daughter Katrina, and her four children, Taye, Ryan, Ayre and Kadyn, aged eight to 13.

The gruesome discovery was made on a farm in Osmington at 5:15am (local time).

"Police are currently responding to what I can only describe as an horrific incident in Osmington, 20km northeast of Margaret River," police commissioner Chris Dawson said on Friday.

"It is early in this investigation. Based on what we do know, this is clearly a tragedy."

Several Australian media outlets are reporting Peter Miles, the grandfather, is a suspect - speculating he shot his six family members before turning the gun on himself. On Saturday Commissioner Dawson would not confirm the allegations.

It's the country's worst mass shooting since the Port Arthur massacre in 1996.